From Claude Code Docs · · 2m
Claude Code 2.1.283 Changelog
Claude Code updates for September 25, 2026: improved gateway hints, model management, and error fixes for better user experience.
In brief
Claude Code updates for September 25, 2026: improved gateway hints, model management, and error fixes for better user experience. Claude Code 2.1.283 adds gateway hint headers for grouping user requests and fixes critical errors in model management and tool interactions. Originally reported by Claude Code Docs.
New Gateway Hints
Added x-claude-code-prompt-id to gateway hint headers so LLM gateways can group requests for one user prompt.
Model Management
Added availableModelsMatch managed setting to block new model releases until explicitly listed.
Model Blocking
Added deniedModels managed setting to block specific models even when availableModels allows them.
MCP Tool Outputs
Added MCP tool, WebFetch and WebSearch outputs to tool.output OpenTelemetry span events when OTEL_LOG_TOOL_CONTENT=1.
Prompt Audit
Added /doctor prompt-audit to audit CLAUDE.md files, skills, agents and commands for older model prompting patterns.
Truncated Messages
Added click-to-expand for truncated messages from other sessions in fullscreen mode.
Plugin Errors
Added path to, plugin-dir load-failure entries in stream-json system/init plugin_errors.
Load Testing
Added opt-in load_test_mode block to Claude apps gateway config for testing deployments without sending requests upstream.
Amazon Bedrock
Added mantle upstream provider for Amazon Bedrock’s Mantle endpoint to Claude apps gateway.
Session Fixes
Fixed SDK sessions losing deferred tool calls or finished tool results when a turn ended early.
MCP Progress
Fixed MCP progress notifications being discarded once a long-running tool call moved to the background.
MCP Server Fixes
Fixed stdio MCP servers being left running when the session ended while they were still starting.
HTTP 404 Fixes
Fixed brief HTTP 404 from stateless remote MCP servers leaving them unusable for the rest of the session.
Fable Limit
Fixed weekly Fable limit not appearing in /usage and VS Code usage meters when telemetry is disabled.
Model Picker Fixes
Fixed /model picker showing hardcoded Haiku version and price when ANTHROPIC_DEFAULT_HAIKU_MODEL pins a different model.
Dynamic Workflows
Fixed dynamic workflows started during model fallback running every agent on the fallback model instead of retrying configured model.
Haiku Model Fixes
Fixed DISABLE_PROMPT_CACHING_HAIKU having no effect when Haiku is the session’s main model.
The headline
Claude Code 2.1.283 adds gateway hint headers for grouping user requests and fixes critical errors in model management and tool interactions.
